International Journal of Scientific Engineering and Technology
Volume No.3 Issue No.8, pp : 1111-1114
(ISSN : 2277-1581)
1 Aug 2014
Study and Analysis of Three Phase Voltage Source Inverter Fed Induction
Motor Drive in Various Pulse Width Modulation Techniques
S. Manivannan, S. Veerakumar, P. Karuppusamy, A. Nandhakumar
Department of Electrical and Electronics Engineering,
Bannari Amman Institute of Technology, Erode, Tamilnadu, India
ABSTRACT-The Three Phase Voltage Source Inverter
supplies invariably required variable voltage and frequency of
the adjustable speed drive system. A number of pulse width
modulation (PWM) schemes are used to obtain variable
voltage and frequency supply from an inverter. The most
widely used PWM scheme for a Three Phase Voltage Source
Inverter is carrier based sinusoidal PWM and Space Vector
Pulse Width Modulation (SVPWM). There is an increasing
trend of using SVPWM, because of their easier digital
realization and better DC bus utilization. The study of SVPWM
technique reveals that this technique utilizes DC bus voltage
more efficiently and generates less harmonic distortion when
compared with sinusoidal PWM techniques. The SVPWM
technique has become one of the important PWM technique
for Three Phase Voltage Source Inverter for the control of AC
induction motor, Brushless DC motor, Switched Reluctance
motor and Permanent Magnet Synchronous motor. In this
paper having collection of different schemes in SVPWM.
Specifically various schemes are Center aligned two level
SVPWM, Level shifted multi-carrier concepts based SVPWM,
and Third order harmonic injection based modulated reference
waveform generation and comparison in SVPWM. This paper
having simulation results of all the three schemes of SVPWM
by using MATLAB/SIMULINK software. The performance of
Three Phase Voltage Source Inverter fed induction motor drive
based on various SVPWM schemes are analyzed by various
reference parameters like DC bus utilization, Total harmonic
distortion (THD), switching stress and efficiency. As a result of
these analysis this paper recommends which scheme is more
suitable for variable voltage and various frequency drives. The
simulation results are provided to validate the proposed model
approaches.
Keywords: Three Phase Voltage Source Inverter, Space vector
Pulse width Modulation (SVPWM), Modulated reference
waveform, Center aligned, Third harmonic injection, Total
Harmonic Distortion (THD), and Switching Stress.
I. INTRODUCTION
Three phase voltage source inverters are widely used in
variable speed AC motor drive applications since they provide
variable voltage and variable frequency output through pulse
width modulation control [1] [2]. The most widely used PWM
method is the carrier-based sine-triangle PWM method due to
simple implementation in both analog and digital realization [2]
[3]. However in this method the DC bus utilization is low
(0.5Vdc). This has led to the investigation into other techniques
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with an objective of improving in the DC bus utilization [1] [3].
The PWM technique termed as Space Vector PWM based on
space vector theory was proposed by de Broeck et. Al (1988)
and Ogasawara et.al (1989) which offers superior performance
compared to the carrier –based sine-triangle PWM technique I
terms of higher DC bus utilization and better harmonics
performance [3]. Further, this technique offers easier digital
realization. The research in PWM schemes has intensified in the
last few decades. The main aim of any modulation technique is
to obtain a variable output with a maximum fundamental
component and minimum harmonics [3] [4].
The problem of underutilization of the DC bus voltage
led to the development of the Third harmonic-injection PWM
(THIPWM) and Space Vector PWM (SVPWM) [5] [6]. In 1975,
Buja developed this improved sinusoidal PWM technique which
added a third –order harmonic content in the sinusoidal reference
signal leading to a 15.5% increase in the utilization rate of the
DC bus voltage. In 1988, Van Der Broeck developed the
SVPWM technique which has also increased the utilization of
DC bus voltage by 15.5% [7] [8].
In the last three decades there are different SVPWM
schemes are developed by various authors. But this paper is
mainly focus on important five schemes in SVPWM. The
various schemes in SVPWM are a) Center aligned two level
SVPWM, b) Level shifted multi-carrier concepts based
SVPWM, and c) Third order harmonic injection based
modulated reference waveform generation and comparison in
SVPWM. Here these three techniques have similar results, but
their methods of implementation are completely different. With
the development of microprocessors SVPWM has become one
of the most important PWM methods for three phase inverter.
The maximum peak fundamental magnitude of the SVPWM
technique is about 90.6% increase in the maximum voltage
compared with conventional sinusoidal modulation [9] - [10].
This paper having some collective information
regarding various schemes as mentioned above presents in the
two level SVPWM based Three Phase Voltage Source Inverter
fed induction motor drive. This paper covers entire concepts
presents in all the three schemes and also this paper gives a
comparative statement regarding all those five schemes. The
comparative statement is developed by the following valuable
parameters. The parameters are THD, DC bus utilization,
switching stress and efficiency. As a result of this comparative
statement the reader can identify which scheme is more suitable
for particular drive operation. The simulation results are
provided to validate the proposed approaches.
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International Journal of Scientific Engineering and Technology
Volume No.3 Issue No.8, pp : 1111-1114
II.
CENTER ALIGNED TWO LEVEL SVPWM
The figure-2 space vector diagram for two-level
inverter shown below should satisfy the above two
requirements. This space vector diagram is common to all the
four possible switching sequences. Only changes in this
space vector diagram are the various possibilities of reference
(ISSN : 2277-1581)
1 Aug 2014
vector rotation in each sectors. The possible switching
sequence in each sector is like, starting with [000] switching
sequence and also ends with [000] switching sequence. This
will be shown in figure-6.1The seven segments switching
sequence and switching time calculation for each switch for
each sector is shown in figure 2.1 to 2.6. The circuit diagram
is
shown
in
figure.
Figure-2 Center aligned SVPWM fed induction motor drive
Figure 2.1 to 2.6 shows a typical seven segment switching

sequence and inverter output waveforms for Vref in each sectors.

  
Here Vref is synthesized by V1 ,V2 &V0 . The sampling period
Ts is divided into seven segments for the selected vectors. The
following can be observed.The dwell time for the seven
segments adds up to the sampling periods, Ts = Ta + Tb + T0.
The design requirement (a) is satisfied. For instance the
transition from [000] to [100] is accomplished by turning S1 ON
and S4 OFF, which involves only two switches. The redundant
switching state are utilized to reduce the number of switching’s
per sampling period. For T0/4 segment in the center of the
sampling period, the switching state [111] is selected, whereas
for the T0/4 segments on both sides, the state [000] is used. Each
of the switches in the inverter turns ON and OFF once per
sampling period. The switching frequency fsw of the devices are
thus equal to the sampling frequency fsp, ie) fsw = fsp = 1/Ts [18].
The performance parameters of the three phase two level
inverter fed induction motor drive are measured and shown in
the figure-3.1 to 3.6.
III.
LEVEL SHIFTED MULTI-CARRIER CONCEPTS
BASED SVPWM
With reference to the figure 2.1 to 2.6 takes the output
from the switches 1 to 6 and compare with carrier signals to
produce the pulses for each switches presents in the three phase
2-level SVPWM Inverter power circuit. The circuit diagram is
shown in figure-4. The performance parameters of the three
phase two level inverters are measured and shown in the figure4.1
to
4.6.
Figure-4 Level shifted multi-carrier concepts based SVPWM
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International Journal of Scientific Engineering and Technology
Volume No.3 Issue No.8, pp : 1111-1114
IV. Third Order Harmonic Injection Based Modulated
Reference Waveform Generation And Comparison
In Svpwm
The Matlab/Simulink diagram for this third order
harmonic injection SVPWM fed induction motor drive is
shown in figure-11. The main blocks available in the diagram
are three phase 50 Hz sinusoidal waveform generator, single
phase 150 Hz sinusoidal waveform generator, summer, carrier
(ISSN : 2277-1581)
1 Aug 2014
waveform generator, comparator, three phase bridge circuit
and induction motor drive. The measurement units are
connected to measure the various performance parameters of
the three phase voltage source inverter fed induction motor
drive.
Figure-6. Third order harmonic injection based SVPWM fed induction motor drive
The simulation procedure for the above Matlab/Simulink circuit
is given below.
a) The first step is to generate three phase 50 Hz sinusoidal
waveforms.
b) The second step is to generate single phase 150 Hz
sinusoidal waveform.
c) The third step is add these two waveforms, we get the
waveforms like modulated sinusoidal reference waveforms.
d) The next step is to compare this modulated reference
waveforms with carrier waveform and generate the pulses
for that switches presents in the three phase voltage source
inverter circuit.
e) The simulated waveforms are available in figure-6 that
shows the performance characteristics of three phase voltage
source inverter fed induction motor drive.
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International Journal of Scientific Engineering and Technology
Volume No.3 Issue No.8, pp : 1111-1114
V.
CONCLUSION
The SVPWM technique can only be applied to a threephase inverter and it increases the overall system efficiency. The
SVPWM is used for controlling the switching of the machine
side converter. Advantages of this method include a higher
modulation index, lower switching losses, and less harmonic
distortion compared to SPWM. SVPWM research has been
widespread in recent years, making it one of the most popular
methods for three-phase inverters because it has a higher
fundamental voltage output than SPWM for the same DC bus
voltage. The SVPWM is significantly better than SPWM by
approximately 15.5%. However, the SVPWM technique is
complex in implementation, especially in the over-modulation
region. SVPWM technique has become the most popular and
important PWM technique for three phases VSI for the control
of AC induction. This paper has provided a thorough review of
the each technique with a special focus on the operation of
SVPWM in all the three possible switching schemes. In this
paper, Simulink models for all three possible switching schemes
has been developed and tested in the MATLAB/SIMULINK
environment. This paper discusses the advantages and
drawbacks of each switching schemes and their simulation
results are compared and analyzed by plotting the output
harmonic spectra of various output voltages and computing their
total harmonic distortions (THD). As seen from the simulation
results the DC bus utilization will be variable for all the three
possible switching schemes, but the THD will be varied for
every switching sequence. From the simulation results we can
come to the conclusion like the methods-II and III switching
schemes having high THD when compared to the other method
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(ISSN : 2277-1581)
1 Aug 2014
of switching schemes. In the future researches there are some
possibilities are available for implementing the same switching
schemes in three phase ZSI and TSI. Definitely the performance
of ZSI and TSI fed induction motor drive will be varied with
respect to its different switching schemes.
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